The present invention relates to a process for introducing a solid into a fluidised or agitated vessel and in particular for introducing a catalytically active solid into a fluidised or agitated vessel. It also relates to an apparatus for carrying out said process.
French Patent Application no 2 562 077 discloses a process and an apparatus for introducing a powdery catalyst into a fluidised bed reactor for the gas phase polymerisation of olefins. The catalyst powder is conveyed into the reactor in the form of a dense and compacted powder,. i.e. in xe2x80x98plug flowxe2x80x99 or xe2x80x98packed bedxe2x80x99 mode. Such xe2x80x98plug flowxe2x80x99 or xe2x80x98packed bedxe2x80x99 flow generally results in poor dispersion of the catalyst inside the reactor causing the formation of hot-spots, and possibly agglomeration of polymer, which may lead to termination of the reaction.
French Patent Application no 2 705 252 discloses a process for introducing a solid into a reactor wherein the solid is first introduced into a feed enclosure and subsequently, on introduction of a gas into the feed enclosure, is suspended in the gas. The gas is introduced into the feed enclosure above the uppermost level of the solid. While this technique already represents an improvement in term of catalyst dispersion, major improvements were still needed in the art.
A process and apparatus have now been found for introducing a solid into a fluidised or agitated vessel without the abovementioned drawbacks i.e. a process and apparatus which provide for improved entry of the solid into the vessel and which also provide for improved dispersion of the solid in the vessel, particularly when a gas phase reactor such as a fluidised bed reactor is used.
Accordingly, the present invention provides a process for introducing a solid particles feed into a fluidised or agitated vessel utilising a feed delivery device, a vertical feed dilution pipe and a feed injection pipe connected to the vessel, said process comprising the following steps:
(a) introducing the solid particles feed from the feed delivery device into the vertical feed dilution pipe,
(b) diluting the solid particles feed by letting the solid particles reaching by gravity their terminal velocity in the feed dilution pipe,
(c) introducing the diluted solid particles feed into the injection pipe and mixing it with a conveying gas, and
(d) introducing said gas conveyed diluted solid particles feed into the Vessel.